from django.db.models import F
from django.shortcuts import render, get_object_or_404
from django.http import HttpResponse, HttpResponseRedirect
from django.views import generic
from django.urls import reverse

from .models import Question, Choice

# Create your views here.

# 使用传统方式
def index(request):
    latest_question_list = Question.objects.order_by("-pub_date")[:5]
    context = {"latest_question_list": latest_question_list}
    return render(request, "index.html", context) # 基于模板，返回一个给定内容的HttpResponse对象


def detail(request, question_id):
    return HttpResponse("You are looking at question %s" % question_id)

def results(request, question_id):
    question = get_object_or_404(Question, pk = question_id)
    return render(request, "polls/results.html", {"question": question})

def vote(request, question_id):
    question = get_object_or_404(Question, pk = question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST["choice"])
    except(KeyError, Choice.DoesNotExist):
        return render(request, "polls/detail.html", {"question": question, "error_message": "You didn't select a choice",},)
    else:
        selected_choice.votes = F("votes") + 1
        selected_choice.save()
        return HttpResponseRedirect(reverse("polls:results", args=(question.id,)))

class IndexView(generic.ListView):
    template_name = "polls/index.html"
    context_object_name = "latest_question_list"

    def get_queryset(self):
        """返回最后五个问题"""
        return Question.objects.order_by("-pub_date")[:5]

class DetailView(generic.DetailView):
    model = Question
    template_name = "polls/detail.html"

class ResultView(generic.DetailView):
    model = Question
    template_name = "polls/results.html"
    